Oil mist lubrication

ABSTRACT

Lubrication of bearings by the placing of a sonic generator in a bearing housing to provide a continuous mist or fog of oil within the housing to lubricate the bearings.

United States Patent Inventor Appl. No.

Filed Patented Assignee Ward F. O'Connor Denville, NJ. 41,393-

May 28, 1970 Oct. 12, 1971 The Lummus Company Bloomfield, NJ.

OIL MIST LUBRICATION 7 Claims, 3 Drawing Figs.

US. Cl

308/78, 308/187 Int. Cl Fl6c 3/14, mac 33/66 [50] Field of Search308/187, 1; 417/241; 184/69; 388/78 [56] References Cited UNITED STATESPATENTS 2,986,433 5/ 1961 Hermann Primary ExaminerEdgar W. GeogheganAssistant ExaminerF rank Susko AttorneyMarn and Jangarathis ABSTRACT:Lubrication of bearings by the placing of a sonic generator in a bearinghousing to provide a continuous mist or fog of oil within the housing tolubricate the bearings.

PAIENTEDuc 12 l9?! Fig. 2.

INVENTOR. Ward F. O'Connor Fig. 3.

ATTORNEYS OIL MIST LUBRICATION This invention relates to the lubricationof bearings for machinery, in particular high speed machinery. Stillmore particularly, this invention relates to oil mist lubrication ofbearings.

There are several methods for applying lubricating oil to bearings,including oil ring spray; drop feed; wick feed; and oil mist or foglubrication. In recent years, there has been considerable interest inoil mist or fog lubrication, but the systems devised to date ate bothcomplicated and costly, thereby making effective use of oil mistlubrication almost prohibitive.

An object of this invention is to provide for improved oil mistlubrication.

Another object of this invention is to provide for lubrication ofbearings by oil mist or fog.

These and other objects of the invention should be readily apparent fromthe following description thereof when read with reference to thefollowing drawings wherein like parts are designated by like numeralsand wherein:

FIG. 1 is a partially cross-sectional view of the bearing structureincluding the sonic generator;

FIG. 2 is a side view of the sonic generator; and

FIG. 3 is a diagram of an embodiment of a circuit which may be used withthe generator of FIG. 2.

The objects of this invention are broadly accomplished by inserting asonic mist generator in a bearing housing with the inlet of thegenerator being placed in the oil reservoir to draw oil therefrom. Thesonic generator atomizes the oil thereby maintaining a continuous oilmist or fog in the housing which lubricates the bearings.

This invention will be described in more detail with reference to theaccompanying drawings which are illustrative of an embodiment of theinvention, but it is to be understood that the scope of the invention isnot to be limited thereby.

Referring now to FIG. 1, there is shown a bearing housing containingbearings l l rotatably supporting a shaft 12. The housing 10 supportsand surrounds the bearing 11, conventionally comprised of an inner race13, rolling elements or balls 14 and outer race 15, the housing 10including a space 16 at the outer side of bearing 11, and a chamber 17at the inner side of bearing 11, the bottom portion of the chamber 17defining a sump or reservoir 18. The space 16 is in fluid flowcommunication with the sump 18 through vertical passage 21 anddownwardly inclined passage 22, the passages 21 and 22 returning oilfrom space 16 to the sump 18.

The shaft 12 extends through a cover 23 closing the housing 10 and isoperatively connected to suitable machinery (not shown), for example, apump, compressor, turbine or the like. The side of the housing 10opposite to cover 23 is also closed by a suitable plate or coverindicated as 24.

The upper portion of the housing 10 is provided with an oil vent 25 anda horizontally disposed oil vent passage 26, which places the upperportion of chamber 17 in communication with the upper portion of space16, thereby preventing any pressure buildup and permitting flow of mistto chamber 16.

A sonic oil mist generator 31 is inserted into the chamber 17 through anappropriate opening 27. The sonic oil mist generator, as shown in moredetail in FIG. 2, is comprised of an electromechanical transducer means,such as a piezoelectric material 32, bonded to an electricallyconductive resonator 33, such as aluminum, comprised of a base portion34 to which the piezoelectric material is bonded, and an elongated topportion 35 of narrower cross section than the base portion 34. Theresonator includes an L-shaped passage 36 comprised of an elongatedportion 37 which extends axially through top portion 35 terminating inan outlet 38 at the top surface thereof, and a shorter portion 39 whichextends radially through the base portion 32 terminating in an inlet 41at the outer periphery thereof. The sonic generator 31 is inserted intothe chamber 17 with the piezoelectric material 32 outside the chamber17, the inlet 41 of passage 36 being below the oil level in sump 18 andthe outlet 38 of passage 36 being above the oil level in sump 18,whereby oil may be drawn into the passage 36 through inlet 41 andreleased through outlet 38 as a fine mist into the portion of chamber 17above sump l8.

The crystal 32 is connected to suitable circuitry which causes thecrystal 32 to vibrate, whereby oil is drawn into the sump 18 through thepassage 36 of the generator 31 and is atomized at the outlet 38 thereof.The sonic generator 31 continuously maintains a mist or fog of oil inthe chamber 17, and

the rotation of the shaft 12 carries oil through the bearings 11 toeffect continuous lubrication thereof. TI-Ie oil whichhas passed throughthe bearings 11 is returned to the reservoir 18 through passages 21 and22.

A suitable circuit for effecting vibration of the crystal isschematically illustrated in FIG. 3, but it is to be understood that thescope of the invention is not limited thereby in that other suitablecircuitry may be devised by one skilled in the art.

Referring now to FIG. 3, there is shown a schematic diagram illustratingan exemplary embodiment of a driver circuit suitable for use inconjunction with the sonic mist generator according to the presentinvention. As is shown in FIG. 3, the exemplary driver circuit comprisesinput terminal means 51 and 52, rectifier means D, and D,, coil meansL,, a silicon controlled rectifier SCR, capacitor means C,, transformermeans T, and a piezoelectric crystal 32. The input tenninal means 51 and52 are adapted to be connected to a standard source of voltage such as avolt, 60 cycle supply as is commonly available at a wall outlet or thelike. The input terminal 51 is connected intermediate the rectifiermeans D, and D, and the input terminal means 52 is connected to theanode of the rectifier means D, The rectifier means D, and D, may takethe form of conventional semiconductor diodes and are connected inseries in a manner such that positive half-cycles of the input signalapplied to input tenninal means 51 will be applied to the coil means L,through rectifier means D, while negative half-cycles of such inputsignals will be applied to conductor 54 through a current limitingresistor R, and rectifier means D,. The coil means L, may take the formof an iron' core inductor or any other circuit means capable ofregulating the rate at which current flows in the illustrated drivercircuit. TI-Ie coil means L, is connected in series with the anode ofthe silicon controlled rectifier SCR, the cathode of diode means D, andthe capacitor means C,. The capacitor means C, may be entirelyconventional in form and is selected to have a value so that the tankcircuit formed therewith, as described below, will oscillate at 25kilocycles. The capacitor means C, is connected in series with theprimary of the transformer means T, which may take the form of an ironcore step-up transfonner having a secondary winding comprising asufficient number of turns to produce a 200 volt output in response tothe application of 110 volts to the input terminal means 51 and 52. Thepiezoelectric crystal 32 is connected, as illustrated in FIG. 3, acrossthe secondary of the transformer means T,, and may be formed of anyknown material capable of producing a mechanical force upon theapplication of a voltage thereto so that ultrasonic energy may beproduced therefrom. Although piezoelectric crystals have been disclosedin specie herein, it will be obvious to those of ordinary skill in theart, that ferroelectric, magnetostrictive or other well-known forms oftransducer material may also be used.

The serial combination formed by the capacitor means C, and the primaryof the transformer T, is connected in parallel with both the seriesbranch formed by the resistor R, and the silicon controlled rectifierSCR and the series branch circuit formed by diode means D, and resistorR, TI-le diode means D, may take the form of a zener diode or otherconventional form of breakdown diode exhibiting a zener or reversevoltage breakdown at a selected voltage. The capacitor means C,, the

primary of the transformer T, together with the reflected im- SCR isconnected to the coil means L, through a relatively large resistor R, sothat said silicon controlled rectifier means SCR is selectively enabledat a voltage which is higher than that selected for the breakdown ofdiode means D The cathode of the silicon controlled rectifier means SCRis connected in series to the current limiting resistor R, so that thecurrent passing therethrough to the conductor 54 is limited to apredetermined value.

in the operation of the embodiment of the driver circuit depicted inFIG. 3, it will be appreciated that upon the application of an inputsignal of 1 volts, 60 cycles to the input terminal means 51 and 52, eachof the positive half cycles therein will be applied to the coil means L,through rectifier means D, while each negative half-cycle thereof willbe attenuated by the current limiting resistor R, and applied throughrectifier means D to the conductor 54. As each positive half-cycle ofthe input signal is applied to the coil means L,, the inductanceexhibited by such coil means L, will tend to oppose the flow of currentassociated with that positive half cycle of the input signal and hencetend to impede current flow toward the capacitor means C,. Thereafter,during the positive half cycle, as current begins to flow in conductor55, the capacitor C, will begin to charge in the well-known manner. Whencharge on the capacitor means C, reaches the zener or reverse breakdownvoltage value selected for the diode means D during the application of agiven positive half-cycle of the input signal thereto, the diode means Dwill breakdown and allow the capacitor means C, to dischargetherethrough thereby releasing energy to the oscillating tank circuitformed by the capacitor means C,, the resistor R and the primary of thetransformer means T,. The tank circuit as thus formed will begin tooscillate in the well-known manner to thereby produce a kilocyclewaveform burst in the primary winding of the transformer means T,. The25 kilocycle waveform burst thus applied to the primary of thetransformer means T, is coupled to the secondary winding thereof in thewell-known manner so that the 25 kilocycle waveform burst producedthereby is increased in magnitude to a value of 200 volts. The 200 volt,25 kilocycle waveform burst produced at the secondary of the transformermeans T, is thus applied across the piezoelectric crystal 32 to causemechanical forces to be produced thereby in the usual manner.

Shortly after the breakdown of the diode means D, during a givenpositive half-cycle of the input signal, the. voltage across resistor R,will increase to a value which is sufficient to trigger on or enable thesilicon controlled rectifier means SCR. When the silicon controlledrectifier means SCR is enabled, virtually all of the current applied toconductor 55 through the coil means L, will pass through the siliconcontrolled rectifier means SCR and the current limiting resistor R toconductor 54. Therefore, at the instant when the silicon controlledrectifier means SCR is enabled, the tank circuit formed by the capacitormeans C,, the primary of the transformer T, and the resistor means Rwill receive no more input energy and hence the 25 kilocycleoscillations produced thereby will subsequently die out due to theattenuation of the oscillating energy therein by the resistive portionof such tank circuit.

Upon the completion of the positive half-cycle of the input signal underdiscussion, the silicon controlled rectifier means SCR will be disabledand a negative half-cycle of the input signal will be applied throughthe current limiting resistor R, and the rectifier means D, to theconductor 54. As such negative half-cycle will not apply energy to thetank circuit, no output signal will be produced by such negativehalf-cycle and hence the piezoelectric crystal 32 will not receive aburst of 200 volt, 25 kilocycle energy during the application of anegative half-cycle of the input signal to the input terminal means 51and 52.

Upon the termination of a negative half-cycle of the input signalapplied to input terminal means 51 and 52, a positive half-cycle of suchinput signal will again be applied to the input terminal means 51 and52. This positive half-cycle of the input signal will again causecapacitor means C, to charge thereby causing the reverse breakdown ofdiode means D,, and the subsequent enabling of the silicon controlledrectifier means SCR in the previously described manner. Accordingly,when these conditions again obtain the tank circuit formed by thecapacitor means C,, the primary of the transfonner means T, and resistorR, will be driven into oscillation and thereby cause the application ofa 200 volt, 25 kilocycle waveform burst across the piezoelectric crystal32. Thus, as each positive half-cycle of an input signal is applied toinput terminal means 51 and 52, the piezoelectric crystal 32 willreceive a 200 volt, 25 kilocycle waveform burst while no energyapplication is received thereby during negative half-cycles of saidinput signal. Therefore, it will be seen that in the exemplaryembodiment of the piezoelectric driver circuit depicted in FIG. 3, a 200volt, 25 kilocycle waveform burst will be applied across thepiezoelectric crystal 32 during each positive half-cycle of the inputsignal applied to input terminals 51 and 52 and that the duration ofsuch 200 volt, 25 kilocycle waveform burst will be shorter than thepositive half-cycle of the input signal associated therewith, therebycausing the crystal 32 to exhibit periodic mechanical vibrations whichis translated to the resonator of the sonic mist generator to which thecrystal is attached.

The exemplary driver circuit hereinabove described with reference toFIG. 3 is a preferred circuit for operating the sonic oil mist generatorof the present invention for lubrication of bearings, but it is to beunderstood that the invention is not to be limited to such an exemplarycircuit as many altematives thereto will be readily apparent to those ofordinary skill in the art. For instance, although the exemplary circuitdepicted in FIG. 3 applies bursts of energy to the piezoelectric crystal32, it will be appreciated that driver circuitry could be employed whichapplies energy to the piezoelectric crystal 32 on a continuous basis.Furthermore, although the foregoing description of FIG. 3 has assumedthe availability of a standard source of alternating current, it will bereadily apparent to those of ordinary skill in the an that a portablebattery supply could be utilized in combination with chopper means orthe input to the exemplary circuit of FIG. 3 could be modified in thewell known manner to directly accommodate a DC input.

The lubrication system may also include a wide variety of other devicesgenerally used in the art, such as constant level oilers, oil throwers,and the like, provided a sonic generator is employed to maintain acontinuous oil mist in the bearing housing. It is ,to be understood thatthe shaft and bearings may be constructed other than as particularlydescribed. Thus, for example, the shaft, bearings and housing may be ofthe type employed for driving a pump or compressor with a turbine, inwhich case the shaft would extend through both sides of the housing, andcontain two sets of bearings, with the shaft being connected at one endto the turbine and at the other to the pump or compressor. The oil mistor fog produced by the sonic generator lubricates both sets of bearings.These constructions and others should be apparent to those skilled inthe art and are within the spirit and scope of the invention providedsuch constructions include a sonic generator to provide oil mistlubrication of the bearings.

Numerous modifications and variations of the present invention arepossible in light of the above teachings and, therefore, within thescope of the appended claims the invention may be practiced other thanas particularly described.

What is claimed is:

l. in a bearing housing having a shaft rotatably supported by bearingstherein, said housing including an oil reservoir, the improvementcomprising: a sonic generator, including an inlet and an outlet,positioned in the housing, said inlet being in said reservoir to drawoil therefrom, and said outlet being positioned in the housing abovesaid reservoir, whereby said generator maintains an oil mist in thehousing for lubricating the bearings.

2. The bearing house as defined in claim 1 wherein the bearing includesan inner race and an outer race and balls supported thereby, one side ofsaid bearing defining with the housing a first chamber, the lowerportion of said first chamber defining the oil reservoir, the other sideof said bearing defining with the housing a second chamber, the shaftextending through the bearing into the first and second chamber; passagemeans connecting the second chamber with said resevoir to return oilwhich has passed through the bearing to the resevoir, said outlet of thesonic generator extending into the upper portion of the first chamber tomaintain an oil mist in said upper portion.

3. The bearing housing as defined in claim 2 wherein the sonic generatoris comprised of a base portion, a top portion and an electromechanicaltransducer means connected to the base portion, said sonic generatorincluding a passage extending from the sonic generator inlet positionedin the base portion to the sonic generator outlet positioned in they topportion.

tric material.

4. The bearing housing as defined in claim 3 wherein said I sonicgenerator additionally includes driver circuit means connected to saidelectromechanical transducer means for applying electrical input energythereto, said driver circuit means comprising:

an oscillatory tank circuit electrically coupled to said elec- 6. Thebearing housing as defined in claim 5 wherein said oscillatory tankcircuit is coupled by transformer means to said electromechanicaltransducer means and includes therein diode means exhibiting apredetermined reverse breakdown potential.

7. The bearing housing as defined in claim 6 wherein said means forapplying input signals to said oscillatory tank circuit comprises:

means for applying input signals of only one polarity to saidoscillatory tank circuit; and means connected in parallel with saidoscillatory tank circuit for selectively shunting said input signals ofonly one polarity away from said oscillatory tank circuit to therebyselectively disable the application of input signals thereto.

1. In a bearing housing having a shaft rotatably supported by bearingstherein, said housing including an oil reservoir, the improvementcomprising: a sonic generator, including an inlet and an outlet,positioned in the housing, said inlet being in said reservoir to drawoil therefrom, and said outlet being positioned in the housing abovesaid reservoir, whereby said generator maintains an oil mist in thehousing for lubricating the bearings.
 2. The bearing house as defined inclaim 1 wherein the bearing includes an inner race and an outer race andballs supported thereby, one side of said bearing defining with thehousing a first chamber, the lower portion of said first chamberdefining the oil reservoir, the other side of said bearing defining withthe housing a second chamber, the shaft extending through the bearinginto the first and second chamber; passage means connecting the secondchamber with said resevoir to return oil which has passed through thebearing to the resevoir, said outlet of the sonic generator extendinginto the upper portion of the first chamber to maintain an oil mist insaid upper portion.
 3. The bearing housing as defined in claim 2 whereinthe sonic generator is comprised of a base portion, a top portion and anelectromechanical transducer means connected to the base portion, saidsonic generator including a passage extending from the sonic generatorinlet positioned in the base portion to the sonic generator outletpositioned in the top portion.
 4. The bearing housing as defined inclaim 3 wherein said sonic generator additionally includes drivercircuit means connected to said electromechanical transducer means forapplying electrical input energy thereto, said driver circuit meanscomprising: an oscillatory tank circuit electrically coupled to saidelectromechanical transducer means; and means for applying input signalsto said oscillatory tank circuit.
 5. The bearing housing as defined inclaim 4 wherein said electromechanical transducer means is formed ofpiezoelectric material.
 6. The bearing housing as defined in claim 5wherein said oscillatory tank circuit is coupled by transformer means tosaid electromechanical transducer means and includes therein diode meansexhibiting a predetermined reverse breakdown potential.
 7. The bearinghousing as defined in claim 6 wherein said means for applying inputsignals to said oscillatory tank circuit comprises: means for applyinginput signals of only one polarity to said oscillatory tank circuit; andmeans connected in parallel with said oscillatory tank circuit forselectively shunting said input signals of only one polarity away fromsaid oscillatory tank circuit to thereby selectively disable theapplication of input signals thereto.